This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. NPPs are members of the AP (Alkalyne Phosphatase) superfamily. They catalyse the phosphate diester hydrolysis. In eukaryotes, these enzymes are found at cell surfaces, either as transmembrane proteins or secreted ,and hydrolyse extracellular phosphate diesters to afect a variety of biological processes (Jesse G.Zalatan et al., Biochemistry, 2006). The structural study of NPPs will allow to improve our understanding of enzymes catalytic mechanisms and the evolution of new enzyme activities